1 Kings 2:8-9

8Also behold, you have with you Shimei son of Gera, the Benjamite from Bahurim, who cursed me with a grievous curse on the day I went to Mahanaim. But when he came down to meet me at the Jordan, I swore to him by Adonai saying: ‘I will not put you to death with the sword.’

9Now don’t let him go unpunished. For you are a wise man, and you will know how to deal with him, and bring his gray hair down to Sheol with blood.”